A system having a global positioning system mounted on a portable remote terminal for transmitting information of the present position of the terminal to a specific party on the other end of the connection is being put to practical use. For example, when a carrier of the portable remote terminal meets an emergency (such as a traffic accident), the person can transmit information of his or her present position to a specific place (such as a rescue center) so as to take a necessary measure without delay.
As antennas used on such a portable remote terminal, surface-mount type antennas have frequently been used because of the terminal being limited in size. For example, a surface-mount type antenna disclosed in Japanese Patent Non-examined Publication No. H7-221537 has a configuration of a radiator electrode provided by a through hole formed parallel to a principal face of a dielectric substrate and of a through hole formed in the direction of the thickness of the dielectric substrate for electrically connecting a radiator electrode with a feeder electrode. In another example, Japanese Patent Non-examined Publication No. H7-235825 discloses a radiator electrode and a coplanar type feeder line provided on each of the principal faces of a dielectric substrate, wherein the radiator electrode and feeder line are connected by a through hole.
In both of the antennas described above, since high precision is required of the size of the through hole and, further, the input impedance of the antenna is directly affected by a connection made at the through hole, great variations in characteristics were produced between products.
In the case of a surface-mount type antenna disclosed in Japanese Patent Non-examined Publication No. H9-214226, an attempt was made to miniaturize the antenna by embedding the feeder electrode in the substrate. However, productivity was poor because this process required cementing substrates together and, sometimes, great variations in characteristics were produced. In addition, because of a difference of thermal expansion coefficient between the substrate and the feeder electrode, cracks were produced, or stress was accumulated, in the substrate, and, sometimes, variations in characteristics were produced.
Further, an antenna disclosed in Japanese Patent Non-examined Publication No. H11-112221 is designed to achieve miniaturization by such a layout that a feeder electrode is surrounded by a radiator electrode. In this case, a minute distance was preset between the feeder electrode and the radiator electrode early in the designing stage to provide the antenna with required impedance matching.
Accordingly, this type of antenna lacks adjustment means and hence variations in characteristics between products sometimes became considerably great, depending on the manner of fabrication.
Further, in a surface-mount type antenna disclosed in Japanese Patent Non-examined Publication No. H11-74721, it is arranged such that the radiator electrode and the ground electrode are provided on the same principal face, whereas no particular design is made to decrease occupied areas by the two electrodes. Accordingly, the dielectric substrate becomes large in size and, therefore, miniaturization of the antenna has been difficult to achieve.
There has been such a technical problem with these prior art surface-mount type antennas that miniaturization of the product, decreased variations in characteristics between products, and increased productivity and enhanced reliability on the product cannot be attained at the same time.